The common causes of pain when pinching the first joint of the middle finger include contusion, tenosynovitis and some immune system diseases. Some patients suffer contusion at the first joint of the middle finger due to an accidental opposing impulse during sports or daily activities, which in turn causes damage to the joint capsule at the first joint of the middle finger, usually accompanied by localized bruising and swelling. Tendovaginitis is common among typing office workers or people with frequent activity of the middle finger, such as yo-yo enthusiasts, due to frequent activity of the middle finger, resulting in repeated friction of the flexor tendon at the entrance of the tendon sheath, causing tendon sheath hyperplasia and narrowing of the tendon, tendon edema, triggering inflammatory reaction to the pain, which is usually accompanied by symptoms such as jamming and popping when moving. In addition, some people with immune system diseases have symptoms of middle finger joint pain, such as rheumatoid arthritis, systemic lupus erythematosus, dry syndrome and so on. As an accompanying symptom of many diseases, pain in the first joint of the middle finger needs to be further examined in a specialized medical institution before the cause can be clarified. If the pain in the first joint of the middle finger worsens, it is recommended to go to the nearest specialized medical institution for further treatment and recovery.